Manufacture of strontium oxide



14, "19%. J. B. MERGE, JR- 2933329909 MANUFACTURE OF STRONTIUM QXIDEFiled June 10, 1942 Jaws D; Y 431 f? se Patented Aug. 14, 1945 I JamesB: Pierce,- Jr.,' Charlestonfwfiyaq" First National Bank' of Tampaexecutor-f said 7 James B. Pierce, Jr., deceased i Application June 10,1942, serial No. 446,432

1 Claim.

This invention relates to the production of strontium oxide and has forits particular objects the extremely expeditious and economicalmanufacture of a product which is highly per- Fig. 2 is a left endelevation of such furnace including the drive mechanism-therefor; and

Fig. 3 is a central vertical section taken on the line 33 of Fig. 1.

' Referring to the drawing and construction shown therein, the referencenumeral I designates an oscillatory barrel or drum having circular railsor tracks 2 externally mounted thereon which are supported on idlerrollers 3, 3' and a driving roller 4, having a stub shaft 4', saiddriving roller being driven by a belt 5 which is reeved over its stubshaft and over a driving pulley 6 carried by a drive shaft 1. The saidfurnace has opposed electrodes 8, 8' which extend axially into the drumthrough the respective ends thereof and a lateral charging aperture 9,normally closed but not hermetically sealed by a door Ill, admits of theintroduction into the drum of a charge of material to be fired. I

In carrying out my improved method the barrel is partially filled,through the door thereof, with a charge comprising equimolecular weightsof ashless carbon black and strontium carbonate, the latter beingdesirably prepared in the manner described in my prior Patent No.1,782,830 of November 25, 1930. The door is then closed but not sealedin order to permit of the maintenance of an envelop of CO, atatmospheric pressure, over the charge during the firing thereof. Thecircuit through the electrodes 8, 8' is then closed and an arcsufficient to maintain a temperature of about 1200 C. is establishedtherebetween. The furnace is constantly oscillated to-and-fro, throughan arc of approximately 185, in order to promote the rapid evolutionfrom the charge of the carbon monoxide gas generated by the reaction.When the reaction is completed, usually in about 2 hours, the furnace isallowed to cool and the resultant strontium oxide recovered.

Since the heat from the electric arc is internally supplied to thecharge, it will be concentrated directly against the reacting mass andbe far more efficient than if the same amount of heat input weresupplied through the wall of a muflie furnace such as employed in themethod disclosed in my aforesaid patent. Furthermore, there is.no knownrefractory that is capable of standing up for any substantial length oftime if the same amount of heat in British thermal units at 1200 C.,were indirectly applied through a muflie to the charge as is supplied tothe charge when employing the electric arc in accordance with myinvention, this being due to the high temperature drop in passingthrough the muffle as compared with the relatively low temperature dropbetween the arc and the charge, since in the latter case the heatdeveloped by the arc has only to pass through the evolved carbonmonoxide gas at atmospheric pressure.

But about one-sixth the time is required in my new process, where theheating of the charge is direct, as compared with my prior processemploying a muffle furnace, because of the greater heat input of theelectrodes employed and the absence of any partial pressure of anycarbon dioxide over the reacting mass or charge such as is inevitablypresent in a muilie furnace due to the leakage or permeation through thewall of the mufiie of the combustion gases. Furthermore the practicallycomplete absence of carbon dioxide within the furnace permits thereaction to proceed to completion at the same temperature with fargreater rapidity than if there were any partial pressure of CO2 over thereacting mass. Likewise, the free escape through the closed but notcompletely sealed door of the carbon monoxide developed in the reaction,insures that the partial pressure of the C0 will not be aboveatmospheric pressure and thereby the velocity of the reaction issubstantially increased. Also, as above stated, the oscillation of thefurnace facilitates the rapid evolution of the gaseous carbon monoxidereaction product and as a consequence, the most effective heating of thecharge can be realized and the velocity of the reaction is a maximum forthe temperature employed.

The resultant strontium oxide product obtained in my process as abovedescribed is ideally adapted for the production of strontium peroxidethe same being soft, flaky and remarkably permeable and consequentlyhighly reactive to oxygen. In fact, at pressures not exceeding 800 lbs.per square inch at least of such oxide can be converted by oxidationinto strontium peroxide.

While I preferably employ ashless carbon black as the reducing agent ofthe charge, other forms of substantially pure, finely divided freecarbon may be substituted therefor such for example as finely powderedcoke or ashless tar and the like.

The temperature employed is preferably 1200 C. but inany event it shouldbe in excess of 1100 C. and sufficient to effect the approximatelycomplete reduction of the strontium carbonate in the charge to strontiumOXide.

Various modifications of the within described method of making strontiumoxide within the scope of the claim may be made without departing fromthe spirit of my invention.

Having thus described my invention, what I claim is:

The method of making strontium oxide which comprises confining a chargeconsisting of substantially equimolecular weights of free carbon andstrontium carbonate in a substantially closed chamber and thereinsubjecting the same to the heat of an electric arc of an intensitysufiicient to heat the charge to a calcining temperature, not less than1100 C., while continually maintainingover the charge, during'the firingthereof, an envelope of nascent carbon monoxide at substantiallyatmospheric pressure and substantially free

